US Patent 7129816 Remote control system

Provided is a remote control system capable of preventing a key code from being deciphered when the key code is transmitted from a transmitter to a receiver to be registered. In the transmitter, in response to a specified switch operation, a k-th common key code in a table to be used for enciphering a key code is changed to a registration key code stored in advance so that a key code is enciphered through the use of the table including the registration key code. A transmission code is produced by adding a predetermined code to the enciphered key code and the transmission code signal is transmitted to the receiver. This prevents easy deciphering of the key code because the key code is transmitted in a state enciphered.